1. Technical Field
The present disclosure relates to a six-blade biaxial rotary positive-displacement pump utilizable in recovery equipment for recovering a carbon dioxide (CO2) gas emitted from electric power generating stations, steel plants and the like, and apparatuses for improving water quality of contaminated water in closed water areas such as rivers, lakes or ponds and sewage water discharged from septic tanks.
2. Related Art
Gear pumps and vane pumps have conventionally been used as pumps for transferring fluids such as water, oil, fuels or the like. Japanese Patent Application Publication No. JP-A-S62-129589 discloses a gear pump comprising a housing having a liquid suction port and a liquid discharge port and a pressurizing surface, a pair of gears (spur wheel gears) which are accommodated in a chamber so as to be rotatable while in mesh engagement with the pressurizing surface with a predetermined gap being interposed therebetween, and a device for adjusting the gap between the gears and the pressurizing surface.
On the other hand, Japanese Patent Application Publication No. JP-A-H06-498 discloses a vane pump comprising an annular rotor and a wave rotor both of which are accommodated in a casing so as to be rotatable in a mesh engagement state. The annular rotor has six radial cylinder ports into which plate-shaped pistons are inserted so that vanes loosely inserted into the bottoms are extruded via springs, respectively. A support shaft having two ends fixed to the casing is inserted into the annular rotor in parallel with a rotation axis of the annular rotor. The vanes have respective distal ends which are elastically adjacent to a circumferential surface of the support shaft.
In the above-described conventional gear pump, the housing includes upper and lower housing members and a central adjustable slider plate which is interposed between the upper and lower housing members so as to be slidable. The central adjustable slider plate has first and second enlarged lobes disposed on inner surfaces of the chamber of the slider plate. A pump efficiency is low in the above-described gear pump since spaces defined between the first and second lobes and gears are large. Furthermore, it is disclosed that the aforementioned gap can be adjusted by an adjusting screw without disassembly of the gear pump and replacement of components. However, an adjusting work is troublesome.
In the above-described conventional vane pump, there is sometimes a case where the pistons and/or the vanes sometimes get into the annular rotor thereby not to be smoothly infested. In this case, the fluid flows backward in the pressurizing chamber, whereupon the performance of the pump is reduced.
Additionally, each of the above-described gear and vane pumps has a small capacity per revolution and tends to produce large oscillation or vibration when driven at 1000 rpm or above for the purpose of increasing the capacity.